Disclosed herein is a process for preparing a device having a superoleophobic surface comprising providing a substrate; using photolithography to create a textured pattern on the substrate wherein the textured pattern comprises polymeric overhang structures; and chemically modifying the textured surface by disposing a fluorinated coating thereon; to provide a flexible device having a superoleophobic surface. The flexible, superoleophobic device can be used, for example, as a front face surface for an ink jet printhead.
Fluid ink jet systems typically include one or more printheads having a plurality of ink jets from which drops of fluid are ejected towards a recording medium. The ink jets of a printhead receive ink from an ink supply chamber or manifold in the printhead which, in turn, receives ink from a source, such as a melted ink reservoir or an ink cartridge. Each ink jet includes a channel having one end in fluid communication with the ink supply manifold. The other end of the ink channel has an orifice or nozzle for ejecting drops of ink. The nozzles of the ink jets may be formed in an aperture or nozzle plate that has openings corresponding to the nozzles of the ink jets. During operation, drop ejecting signals activate actuators in the ink jets to expel drops of fluid from the ink jet nozzles onto the recording medium. By selectively activating the actuators of the ink jets to eject drops as the recording medium and/or printhead assembly are moved relative to one another, the deposited drops can be precisely patterned to form particular text and graphic images on the recording medium.
One difficulty faced by fluid ink jet systems is wetting, drooling or flooding of inks onto the printhead front face. Such contamination of the printhead front face can cause or contribute to blocking of the ink jet nozzles and channels, which alone or in combination with the wetted, contaminated front face, can cause or contribute to non-firing or missing drops, undersized or otherwise wrong-sized drops, satellites, or misdirected drops on the recording medium and thus result in degraded print quality. Efforts to address these issues have relied upon printhead front face coatings. Current printhead front face coatings are typically sputtered polytetrafluoroethylene coatings. When the printhead is tilted, the UV gel ink at a temperature of about 75° C. (75° C. being a typical jetting temperature for UV gel ink) and the solid ink at a temperature of about 105° C. (105° C. being a typical jetting temperature for solid ink) do not readily slide on the printhead front face surface. Rather, these inks flow along the printhead front face and leave an ink film or residue on the printhead which can interfere with jetting. For this reason, the front faces of UV and solid ink printheads are prone to be contaminated by UV and solid inks. In some cases, the contaminated printhead can be refreshed or cleaned with a maintenance unit. However, such an approach introduces system complexity, hardware cost, and sometimes reliability issues.
There remains a need for materials and methods for preparing devices having superoleophobic characteristics. Further, while currently available coatings for ink jet printhead front faces are suitable for their intended purposes, a need remains for an improved printhead front face design that reduces or eliminates wetting, drooling, flooding, and/or contamination of UV or solid ink over the printhead front face. There further remains a need for an improved printhead front face design that is ink phobic, that is, oleophobic, and robust to withstand maintenance procedures such as wiping of the printhead front face. There further remains a need for an improved printhead front face design that is superoleophobic. There remains a further need to develop simple, cost-effective processes to create superoleophobic textures on large area flexible substrates.